Process and apparatus for forming metal objects



July 8, 1924-" E. GOODSPEEDI PROCESS AND APPARATUS For: FORMING METAL OBJECTS Filed A112. 25; 1920 Y. QWMW :A r L1 [w W MN\ 1 LI xw v Y FQ & Q Q Q m\ wm Mm Wei? fi a MN V M m WHE v MU WHHMMHMHU Patented July 8,1924.

UNITED STATES PATENT OFFICE.

ELVIN S. GOODSPEED, DETROIT, MICHIGAN, ASSIGNOR TO GENERAL MOTORS COB- PORATION, OF DETROIT, MICHIGAN, A CORPORATION OF DELAWARE PROCESS AND APPARATUS FOR FORmNG METAL OBJECTS.

Application filed August 25, 1920. Serial Ira-405,906.

To all whom it may concern Be it known that I, ELVIN S. Goonsrnnn, a citizen of the United States, and a resident of Detroit,.county of Wayne, and State of Michigan, have invented certain new and useful Improvements in Processes and Apparatus for Forming Metal Objects, of which the following is-a full, clear, concise, and exact description, such as will enable others skilled in the art to which the invention relates to make and use the same, reference being made therein to the accompanying drawings, which form a part of this specification.

The invention relates to a process and ap paratus especially adapted for forming metal objects and more particularly to such a process and apparatus in which an electric current is employed for the purpose of heating and softening the metal preliminary to or during the progress of the forming operation.

The object of the invention is to provide for the formation of an article by a combined upsetting and expanding operation while the blank is in a plastic condition.

A further object is to provide for the formation of a hollow article from a heated plastic blank by means of internal pressure, preferably under the influence of a fluid pressure medium.

A further object is to provide for the formation of a hollow article by the combined upsetting and expanding of an electrically heated blank within a pair of relatively movable mold members.

With the above and other objects irrview as will appear more fully from the following description the invention consists of the features of novelty hereinafter described and set forth in the claims, it being understood that many variations in specific details may be made by one skilled in the art without departing from the spirit and scope of the invention.

In the accompanying drawings illustrating a form of apparatus adapted to carry.

out the process of the invention.

Figure 1 is an elevation of the apparatus with parts shown in section, and

Figure 2 is an enlarged detail view showing the mold members in the position which will be assumed when the forming operation has been completed. 7

In the drawings, 5 and 6 indicate frame members of any suitable character adapted to support the parts of the forming mechamsm and connected by guides 7. The mold members 8, 9, will be supported upon the guides in such manner that one, at least, of the members may be moved along the guides so that when the two members are brought into proximity the mating recesses 10, 11, formed in the faces thereof will enclose a space corresponding to the shape of the article which it is desired to produce. As shown the member 9 may be permitted to rest against a portion of the frame 6 while the member 8 may be arranged to be moved longitudinally of the guides as by'a ram 12 operated in any suitable manner as bya pzigston traveling in a fluid pressure cylinder 1 Electrodes 14, 15, arranged to contact with the blank held in the members 8', 9, are connected to the secondary circuit of a transformer 17 in order to supply a heating current of large amperage to the said blank. The heating current may be arranged to be controlled in any appropriate manner, as by an electrically operated switch in the primar circuit 18 of the transformer.

Insu ating means will be rovided of course where necessary to con e the path of the current to that portion of the blank between the electrodes.

When the articles to be formed comprise anenlargement intermediate the ends of a blank, as when an irregular formation is to be produced in an intermediate portion of a tubular blank, the mold members 8, 9, will be formed with apertures, as at 21, 22, through which the ends of the blank will be permitted to extend. The blank is shown by way of example as a tube at the intermediate portion of which is to be formed an enlargement corresponding to that occurring in a conventional axle housin The ends of the blank will be supported in such manner that endwisepressure may be exerted thereon, as against the frame 6 and the ram 12 respectively. When the blank is tubular the ends will be suitably sealed as at 23, 24, and a means for the supply of fluid pressure medium, as a pipe 25, maybe arranged in any appropriate manner to supply a suitable ressure medium to the interior of the tu e. The source of pressure medium will referably be such that the pressure may go varied at will. As shown v a pressure supply pipe 26 adapted to supply,a fluid at low pressure is arranged to operate a differential piston mechanism 27 wiereby pressure medium at higher pressure may be provided as desired.

In the practice of the process a suitable blank may be mounted in the apparatus as already'described, the mold membersbeing at such distance from each other as may be determined by the amount of metal required in the formation of the article. The electric current being turned on, the blank is brought to the desired degree of plasticity between the points where it contacts with the electrodes. Fluid pressure will be applied in the meantime suflicient to prevent the blank from buckling and preferably sufiicient to cause it to become some- 4 sary to cause the expanded metal to assume the exact contour of the mold recess. While the apparatus as shown provides for the simultaneous movement of the mold mem bers and upsetting of the blank it will be seen that the two operations need not be necessarily simultaneously nor coextensive. If the apertures in the mold members through which the blank extends are such asjto permit a relative slidin movement of the; said members and the bdank the mold may be entirely closed before the upsetting movement begins, suitable mechamsm being provided to render these movements in-- dependent or non-synchronous. Furthermore the two movements may be made simultaneous but with any desired variation in relative rates.

The current may be turned off after the metal has reached the desired degree of plasticity necessary to permit the completion of t e shaping operation. The metal, as will be obvious, will be guickly cooled by contact with the walls 0 the mold or die and may be then removed from the apparatus.

particular advantage of rendering possible the formation of an enlargement or expanded structure without decreasing the thickness of the walls thereof, since the upsetting operation provides the additional metal necessary to maintain or even to increase the thickness of the expanded portion. 7 1

It will also be understood that the use of external means for supplying fluid pressure medium during the progress of the. forming operation may not be necessary in all cases. It may be sufficient to place in the blank preliminarily a charge of ressure medium suflicient to produce the esired pressure, or merely to seal the ends of the blank thereby confining therein the air normally present in the interior, the necessary pressure being produced by the expansion of the air under the influence of the heat developed by the passage of the electric current.

I claim:

1. The process of forming articles which comprises supporting a hollow blank within a mold recess, heating the, blank While thus supported to a temperatureflat which it becomes plastic, applying pressure to the 1 interior of said blank to cause the same to expand within the mold recess, and simultaneously reducing the length of the blank to provide additional material for the wallsof the blank within the mold recess.

2. The process of forming articles which comprises supporting a hollow blank within mold members said blank being heated to a temperature at which it becomes plastic, supplying to the interior of said blank a gaseous uid pressure medium. adapted to cause the expansion of the same to take the form of the mold, and shortening the blank to provide additional material for the walls of the blank within the mold.

3. The process of'forming articles which comprises supporting a blank between mold members having recesses therein, applying an electric current to heat the blank, causing the die members to approach each other when the blank becomes plastic, and causing the blank to be upset to conform to the said recesses.

4. The process of forming articles which comprises supporting a hollow blank within mold members, heating the blank by the passage of an electric current therethrough, reducmg the length of the blank, and causing it to expand y the influence of internal pressure.

5; The process of forming articles which comprises supporting a hollow blank between mold members, heating the blank by the passage of an electric current there. throu h, causing the mold members to approac each other, shortening the blank, and causing it to exp-and by su plying fluid medium to the interior thereo under pressure.

6. In molding apparatus the combination of a plurality of mold members problank to cause the same to be upset within vided with recesses and apertures communisaid recesses, and means for supplying -a 10 catin therewith adapted to receive a tubufluid pressure medium to the intenor of said lar b ank with its ends extending through blank.

'5 said apertures, means carried by said mo (1 In testimony whereof I aifix my signamembers adapted to transmit electric'curture. rent through the said blank, means for a plying pressure longitudinally of said ELVIN S. GOODSPEED. 

